Chromophore-containing compounds for opto-electronic applications

Abstract

The use of a multi-functional, chromophore containing, polymerizable compound for producing an optical element having non-linear optical properties (an NLO element) wherein the multi-functional chromophore is a compound capable of being polymerized into a cross-linked network and of being poled under the influence of an electric field whilst being polymerized into the cross-linked network, the compound having the generalized formula (D) (C) (A) (F) D, C, A and F representing covalently linked moieties where C represents at least one conjugated system of π-bonds, A and D represent at least one respectively π-electron acceptor and π-electron donor groups linked at opposite ends of the conjugated system, and are preferably conjugated with the conjugated system of π-bonds (C) and where more than one moiety A, C or D is present they may be the same or different, F represents at least two polymerizable functional groups, which may be the same or different, attached to the π-conjugated system C or the groups A and D via substituent groups R 1 , and R 2 , where R 1 and R 2 are selected from alkyl, cycloalkyl, aryl heteroalkyl, alkenyl, cycloalkenyl, and alkynyl including groups which have been substituted or contain heteroatom replacement, the groups F being linked to the compound so that after the compound has been polymerized to give a cross-linked network the interpolymerized functional groups prevent significant realignment of the chromophore groups when the optical element is subject to temperature changes during any further fabrication and in use.

We claim: 
     
       1. An optical element having non-linear optical properties comprising a multi-functional, chromophore containing, polymerizable compound wherein the multi-functional chromophore is a compound capable of being polymerized into a cross-linked network and of being poled under the influence of an electric field while being polymerized into the cross-linked network, the compound having the generalized formula   (D) (C) (A) (F)     D, C, A, and F representing covalently linked moieties where C represents at least one conjugated system of π-electron donor groups linked at opposite ends of the conjugated system C; an F represents at least two polymerizable functional groups, which may be the same or different, attached to the π-conjugated system C, group A or group D via substituent groups R 1  and R 2  ; and R 1  and R 2  are independently selected from such groups as alkyl, cycloalkyl, aryl heteroalkyl, alkenyl, cycloalkenyl, and alkynyl groups, substituted variants of such groups and heteroatom-containing variants of such groups wherein at least one carbon atom has been replaced by a heteroatom, the groups F being linked to the compound so that after the compound has been polymerized to give a cross-linked network the interpolymerized functional groups prevent significant realignment of the chromophore groups when the optical element is subject to temperature changes such that after annealing the optical element at 60° C. for 1 hour the normalized second harmonic generation intensity (SHG) fall by less than 10% if the optical element is held at 60° C. for 1000 hours.   
     
     
       2. An optical element as claimed in claim 1 wherein conjugated system C is selected from at least one of an aromatic ring system, a (poly)ene system containing at least one conjugated π-bond, a (poly)yne system containing at least one conjugated acetylene bonds, a quinomethide system or heteroatom-containing variants of such systems wherein one or more carbon atoms and/or one or more C═C double bonds are replaced by a heteroatom. 
     
     
       3. An optical element as claimed in claim 1 wherein the π-electron donor group D is appended to the conjugated system C and is selected for the groups amino, NR 1  R 2  ; thio, SR 1  ; oxy, OR 1  ; phosphino, PR 1  R 2 ,, where R 1  and R 2  are independently selected from such groups as alkyl, cycloalkyl, aryl heteroalkyl, alkenyl, cycloalkenyl, and alkynyl groups, substituted variants of such groups and heteroatom-containing variants of such groups wherein at least one carbon atom has been replace by a heteroatom. 
     
     
       4. An optical element as claimed in claim 1 wherein the π-electron acceptor group A is selected from the groups nitro, NO 2  ; cyano, CN; nitroso, NO; ester, CO 2  R 1  ; amide, CONR 1  R 2 , ketone COR 1  ; formyl, COH; sulphone, SO 2  R 1  ; sulphoxide, SOR 1  ; sulphonate ester, SO 3  R 1  ; sulphonamide, SO 2  NR 1  N 2  ; phosphonate, P(═O)OR 1  OR 2  ; phosphine oxide, P(═O)R 1  R 2  ; boronate ester, B(OR 1 )OR 2  ; N-pyridium where R 1  and R 2  are independently selected from such groups as alkyl, cycloalkyl, aryl heteroalkyl, alkenyl, cycloalkenyl, and alkynyl groups, substituted variants of such groups and heteroatom-containing variants of such groups wherein at least one carbon atom has been replaced by a heteroatom. 
     
     
       5. An optical element as claimed in claim 1 wherein each of the at least two polymerizable groups represented by F are independently selected form acrylate ester, methacrylate ester, acrylamide, methacrylamide, epoxide, isocyanate, cyanate, hydroxy, amino or maleimide groups. 
     
     
       6. An optical element as claimed in claim 1 wherein each of the at least two polymerizable groups represented by F are selected such that during the polymerization step (c) the cross-linking of the polymeric structure by the polymerizable groups is achieved by a non-elimination reaction. 
     
     
       7. An optical element as claimed in claim 1 wherein the group F comprises a first polymerizable group F 1  and a second polymerizable group F 2  which are different from and polymerizable with one another but which are substantially not polymerizable with others of the same group. 
     
     
       8. An optical element as claimed in claim 1 comprising a cured and poled film. 
     
     
       9. An optical element having non-linear optical properties comprising a multi-functional, chromophore containing, polymerizable compound wherein the multi-functional chromophore is a compound capable of being polymerized into a cross-linked network and of being poled under the influence of an electric field while being polymerized into the cross-linked network, the compound having the generalized formula   (D) (C) (A) (F)     D, C, A, and F representing covalently linked moieties where C represents at east one conjugated system of π-electron donor groups linked at opposite ends of the conjugated system C; F represents at least two polymerizable functional groups, which may be the same or different, attached to the π-conjugated system C, group A or group D via substituent groups R 1  and R 2  ; and R 1  and R 2  are independently selected form such groups as alkyl, cycloalkyl, aryl heteroalkyl, alkenyl, cycloalkenyl, and alkynyl groups, substituted variants of such groups and heteroatom-containing variants of such groups wherein at least one carbon atom has been replaced by a heteroatom, the groups F being linked to the compound so that after the compound has been polymerized to give a cross-linked network the interpolymerized functional groups prevent significant realignment of the chromophore groups when the optical element is subject to temperature changes such that the optical element exhibits and or of less than 50% in the normalized second harmonic generation intensity (SHG) after heating at a rate of 5° C. per minute from ambient to 150° C.   
     
     
       10. An optical element according to claim 9 comprising a cured and poled film.